Reproducibility of increased blood pressure during an emergency department or urgent care visit

Abstract

Study objective: We determine the reproducibility of increased blood pressure measurements among adults in the emergency department or minor injury clinic. Methods: The study was conducted at Kaiser Permanente Medical Center in Hayward, CA, a large, group-model health maintenance organization providing capitated insurance coverage. All patients were included in the study who had no current diagnosis of hypertension but had increased blood pressure on their presentation to the ED or minor injury clinic during the 2-month study period. The staff was asked to repeat the blood pressure later during the index visit and provide these patients with written instructions to return for additional repeat measures. We compared blood pressures taken in the ED to measurements before and after the ED visit. Results: Four hundred seven patients were included in the study. Of the initial elevated blood pressures, 211 (51.8%) were stage 1 elevation, 147 (36.1%) were stage 2, and 49 (12.0%) were stage 3 by criteria of the Joint National Committee on Hypertension. Sixty-five percent of patients had repeat measures in the clinic during our 5-month follow-up period, despite active outreach and reminders. Seventy percent of those who had repeat blood pressure documented had at least 1 increased blood pressure after their ED visit. The proportion of patients with at least 1 abnormal blood pressure on subsequent measurement increased with increasing stage of initial blood pressure (64.4% for stage 1, 77.1% for stage 2, 97.1% for stage 3), but was similar for patients with and without pain as a chief complaint and was similar for patients seen in the ED compared with patients seen in urgent care. Compared with blood pressures taken during the ED visit, matched blood pressures taken before or after showed no statistically significant differences. Conclusion: Increased blood pressure is common among emergency or urgent care patients without a history of current hypertension, and most of these will have mixed or consistently abnormal results on repeat measures. Patients should be referred for repeat measures after a single abnormal measure in the ED. [Ann Emerg Med. 2003;41:507-512.]

Introduction

Hypertension is a leading risk factor for coronary heart disease, stroke, renal disease, and retinopathy.1, 2 Sixty percent of people who are older than 60 years of age have hypertension, yet only half of these are aware of their hypertension and only one third are adequately treated.³ Most emergency departments record blood pressure on all patients, but increased measurements are often discounted and attributed to pain, anxiety, or random elevation, raising the question of whether the ED is an appropriate site for hypertension screening and routine referral.⁴ Previous studies suggest that follow-up blood pressure at a subsequent date in the clinic will exclude one third to one half of those with increased blood pressure in the ED, but as many as two thirds can benefit from further therapy or closer follow-up.4, 5, 6 Additionally, the ED may allow screening of a significant segment of the population, including many who do not make routine appointments.5, 7 Despite evidence that many do require follow-up and that a simple protocol can effectively identify and refer those with increased blood pressure, recognition and follow-up of ED patients with increased blood pressure is often poor.5, 8

Insurance coverage and clinic accessibility in a capitated health maintenance organization differ substantially from the inner-city populations of the aforementioned studies. In a group-model health maintenance organization like Kaiser Permanente where patients are encouraged to establish with a primary care provider and obtain preventive health care, patients with hypertension may have a higher likelihood of being previously identified and monitored. On the other hand, the ED may see many new health maintenance organization members and low-utilizing patients who have not had their blood pressure measured regularly, so the ED visit may offer an important opportunity to screen for hypertension.

The aim of this study was to determine whether increased blood pressure among adults during visits to the ED or minor injury urgent care clinic is predictive of subsequent increased blood pressure measured in clinic.